Severity of Obstructive Sleep Apnea and Its Impact on Retinal Ganglion Cell Complex and Retinal Nerve Fiber Layer

Abstract

Aim: To evaluate whether chronic systemic hypoxia associated with obstructive sleep apnea syndrome (OSAS) is related to structural changes in the retinal ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL). Materials and Methods: This cross-sectional, observational case–control study included 49 OSAS patients and 20 age- and sex-matched healthy controls with a normal apnea–hypopnea index (AHI <5). Participants were aged 30–65 years. Exclusion criteria included systemic or ocular disease, prior ocular surgery, smoking, alcohol use, and refractive error exceeding ±3.00 diopters. All subjects underwent overnight polysomnography. Spectral-domain optical coherence tomography (SD-OCT; Optovue RTVue) was performed in the morning (09:00–11:00) to measure average and sectoral GCC and RNFL thickness. Recorded sleep parameters included AHI, mean oxygen saturation (SpO₂), nadir SpO₂, duration of sleep with SpO₂ between 80–90%, and the percentage of total sleep time spent in this range. Results: No statistically significant differences were observed between the OSAS and control groups for average or sectoral GCC and RNFL thickness (all p>0.05). Correlation analyses showed no significant associations between GCC or RNFL thickness and AHI, mean SpO₂, nadir SpO₂, duration of SpO₂ at 80–90%, or the percentage of sleep time spent in this range (all p>0.05). Sector-based analyses revealed no focal retinal thinning. Conclusion: GCC and RNFL thickness were not associated with OSAS severity or nocturnal hypoxemia parameters. These findings suggest that global hypoxic burden alone may not cause early retinal neurodegeneration. Local ischemic or microvascular factors may be more influential. Larger longitudinal studies including retinal perfusion imaging are needed.

Keywords

• Obstructive sleep apnoea syndrome
• Ganglion cell complex
• Retinal nerve fibre layer
• Hypoxia
• Optical coherence tomography

Ethical Statement

This cross-sectional, observational, case-control study was conducted between 1 June and 1 December 2022 to investigate the impact of OSAS severity on RNFL and GCC thickness prior to treatment initiation. The study protocol was reviewed and approved by the XXX Clinical Research Ethics Committee (Approval No. 2022-5, dated 9 October 2022). All participants provided written informed consent before enrolment, in accordance with the principles of the Declaration of Helsinki.

Obstrüktif Uyku Apnesinin Şiddeti ve Bunun Retina Ganglion Hücre Kompleksi ile Retina Sinir Lifi Tabakası Üzerindeki Etkisi

Abstract

Amaç: Obstrüktif uyku apne sendromunda (OUAS) kronik sistemik hipoksinin retina gangliyon hücre kompleksi (GCC) ve retina sinir lifi tabakası (RNFL) kalınlıkları ile ilişkisini değerlendirmek. Gereç ve Yöntem: Bu kesitsel, gözlemsel olgu-kontrol çalışmasına tedavi almamış 49 OUAS hastası ve apne–hipopne indeksi (AHI <5) normal olan, yaş ve cinsiyet açısından eşleştirilmiş 20 sağlıklı birey dahil edildi. Tüm katılımcılar 30–65 yaş arasındaydı. Sistemik veya oküler hastalık, geçirilmiş göz cerrahisi, sigara veya alkol kullanımı ve ±3.00 diyoptrinin üzerindeki kırma kusurları dışlama kriteri olarak belirlendi. Tüm olgulara bir gece polisomnografi uygulandı. Sabah saatlerinde (09:00–11:00) spektral-domain optik koherens tomografi ile ortalama ve sektörel GCC ve RNFL kalınlıkları ölçüldü. AHI, ortalama SpO₂, en düşük SpO₂, SpO₂’nin %80–90 aralığında geçtiği süre ve bu sürenin toplam uykuya oranı kaydedildi. Bulgular: OUAS ve kontrol grupları arasında GCC ve RNFL kalınlıkları açısından anlamlı fark saptanmadı. Ayrıca GCC ve RNFL kalınlıkları ile AHI ve oksijen satürasyon parametreleri arasında anlamlı ilişki bulunmadı. Sonuç: OUAS şiddeti ve gece hipoksemisi ile GCC ve RNFL kalınlıkları ilişkili bulunmamıştır. Bulgular, erken retinal etkilenmede global hipoksiden ziyade lokal iskemik veya mikrovasküler mekanizmaların daha önemli olabileceğini düşündürmektedir.

Keywords

• Obstrüktif uyku apnesi sendromu
• Ganglion hücre kompleksi
• Retina sinir lifi tabakası
• Hipoksi
• Optik koherens tomografi

Ethical Statement

Bu kesitsel, gözlemsel, olgu-kontrol çalışması; obstrüktif uyku apnesi sendromunun (OSAS) tedavi öncesi evrelerinde retina sinir lifi tabakası (RNFL) ve ganglion hücre kompleksi (GCC) kalınlığı üzerindeki etkisini değerlendirmek amacıyla 1 Haziran – 1 Aralık 2022 tarihleri arasında gerçekleştirilmiştir. Çalışma protokolü, XXX Klinik Araştırmalar Etik Kurulu tarafından değerlendirilmiş ve onaylanmıştır (Onay No: 2022-5, Tarih: 9 Ekim 2022). Tüm katılımcılardan çalışmaya dahil edilmeden önce yazılı aydınlatılmış onam alınmış olup, çalışma Helsinki Bildirgesi ilkelerine uygun olarak yürütülmüştür.

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